Cascade reoxygenation dissolved oxygen control experiment device and method

Abstract

The invention relates to a water body dissolved oxygen control technology, in particular to a cascade reoxygenation dissolved oxygen control experiment device and method. The device comprises a deoxidation system, an oxygenation system, an oxygen stabilizing system, a water supplementing system and an experiment system, wherein the deoxidation system is used for rapidly generating enough low-saturation dissolved oxygen water; the oxygenation system is responsible for realizing continuous increasing of dissolved oxygen in the low-oxygen water body; the oxygen stabilizing system is responsible for keeping the pressure of a water body entering the oxygenation system stable and keeping the flow state of the water body entering the experiment system constant, the water supplementing system is used for automatically, continuously and stably inputting raw water into the deoxygenation system, and the experiment system introduces the water body with the constant dissolved oxygen concentration into the experiment system by simulating an aquatic ecosystem in a test environment; the influence of experimental water bodies with different dissolved oxygen contents on growth, reproduction, behaviors and the like of aquatic organisms under different exposure time is comprehensively reflected, so that the accuracy and reliability of experimental results are ensured.

Description

Technical Field

[0001] The invention relates to a water body dissolved oxygen control technology, in particular to a cascade re-oxygenation dissolved oxygen control experimental device and method. Background Art

[0002] The availability of dissolved oxygen (DO) is a key factor in regulating the function of aquatic ecosystems and an important indicator of the health of aquatic ecosystems. Dissolved oxygen plays a vital role in the survival of aquatic organisms and their physiological and ecological behaviors, and low dissolved oxygen levels are considered to be an important regulatory factor affecting toxic effects. The dissolved oxygen concentration in the aquatic environment is controlled by the balance between sources (i.e., environmental conditions of water mixing with air and oxygen-containing advection) and sinks (including aerobic respiration and abiotic oxidation). Fluctuations in dissolved oxygen concentrations in time and space can trigger a series of biological, chemical and ecological chain reactions.

[0003] Researchers have conducted in-depth studies on the effects of persistent low dissolved oxygen in water and sediments on aquatic organisms. The results show that many aquatic organisms can tolerate short-term low oxygen stress, however, there is still a lack of research on the long-term effects of low dissolved oxygen on the survival, growth and development of aquatic organisms. This situation is closely related to the challenge of continuously and stably controlling the dissolved oxygen concentration at multiple levels in the same laboratory environment for a long time, that is, there is currently a lack of equipment and methods that can accurately, simply and stably control the dissolved oxygen concentration.

[0004] Increasing the amount of dissolved oxygen in water can be achieved by enhancing its mixing with air, while removing oxygen from water can be achieved by physical or chemical means. In the field of biological testing, chemical deoxygenation methods are not commonly used due to possible adverse effects such as direct toxicity or increased solid content of compounds in water. Alternative physical methods include thermal degassing, vacuum degassing and nitrogen stripping. In addition to thermal degassing, vacuum degassing and nitrogen stripping have been widely used in laboratory research due to their relatively simple operation and high efficiency. However, it should be noted that vacuum degassing technology requires higher costs and more complex maintenance and management. In contrast, nitrogen stripping degassing can show more significant cost-effectiveness in the short term.

[0005] Irving developed a water nitrogen deoxygenation system in 2004 specifically for studying the lethal and sublethal toxic effects of hypoxic conditions on invertebrates. The system works by precisely controlling the flow of nitrogen and air in each container through flow meters to achieve a preset level of dissolved oxygen (DO). Subsequently, in 2008, Chan developed a similar water deoxygenation system based on the same principle. The system uses sensors to automatically control the supply of air and nitrogen to ensure that the desired dissolved oxygen level is achieved. It is worth noting that both of the above methods can only produce a specific dissolved oxygen concentration at any given time.

[0006] Also in 2008, Mattson developed a water nitrogen deoxygenation system designed to study the toxic effects of low dissolved oxygen conditions on freshwater biological sediments. The system is able to obtain multiple required DO levels through natural oxygenation of continuous water flow. However, the mixing efficiency of the system is relatively low, and it is not easy to accurately adjust the changes in dissolved oxygen over time. In addition, in order to meet the demand for experimental water volume, the device also needs to be installed with a fractionation column of sufficient height, which is difficult to achieve under many laboratory environmental conditions.

[0007] Based on this, there is an urgent need for a device and method that can accurately, simply and stably control the dissolved oxygen concentration. Summary of the invention

[0008] The purpose of the present invention is to solve the problems existing in the prior art and provide a cascade re-oxygenation dissolved oxygen control experimental device and method.

[0009] In order to solve the problems existing in the prior art, the present invention adopts the following technical solutions:

[0010] A cascade reoxygenation dissolved oxygen control experimental device, comprising:

[0011] A deoxygenation system, wherein the deoxygenation system is used to generate a low-saturation dissolved oxygen water body;

[0012] An oxygenation system, wherein the oxygenation system is used to gradually increase the dissolved oxygen content in the low-saturation dissolved oxygen water body to obtain dissolved oxygen water bodies with different saturations;

[0013] An oxygen stabilization system, the oxygen stabilization system is used to adjust the pressure and dissolved oxygen concentration of the water body with a specific saturation dissolved oxygen obtained by the oxygenation system;

[0014] A test system, wherein the test system is used to simulate an aquatic ecosystem of a test environment, introduce a water body with a constant dissolved oxygen concentration into the experiment, and obtain experimental data;

[0015] Among them, the water body becomes a low-saturation dissolved oxygen water body after passing through the deoxygenation module. According to the dissolved oxygen concentration of the low-saturation dissolved oxygen water, the dissolved oxygen concentration of the water body is adjusted by the oxygenation system, and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system. The test system obtains experimental data through the deoxygenation system, the oxygenation system and the oxygen stabilization system.

[0016] As an improvement of the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, the cascade reoxygenation dissolved oxygen control experimental device also includes a water replenishment system; the water replenishment system is used to provide raw water for the deoxygenation system.

[0017] As an improvement of the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, the deoxygenation system includes a gas supply system for supplying nitrogen, a reactor and an ejector;

[0018] Nitrogen and reaction water are sucked in through the ejector, and the reaction water is circulated and deoxygenated through the circulating water pump.

[0019] As an improvement of the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, the ejector includes a convergent pipe, an air inlet, a diffuser, a check valve and a frequency converter;

[0020] The convergence pipe is arranged at the connection of the ejector nozzle to guide the direction of water flow. The air inlet of the ejector is a vacuum suction roller structure. The ejector sucks the nitrogen into the mixed reaction water.

[0021] As an improvement on the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, a microporous structure unit for air and water intake is arranged inside the reactor, and the microporous structure unit is used to generate nitrogen and water into bubbles and water molecules, thereby prolonging the residence time of the bubbles and water molecules in the water.

[0022] As an improvement of the technical solution of the cascade re-oxygenation dissolved oxygen control experimental device of the present invention, the oxygenation system includes an aerator, the aerator is divided into a plurality of aeration chambers by a movable baffle, and each of the aeration chambers is provided with a water outlet;

[0023] The oxygenator is arranged on a second bracket with adjustable height and / or angle;

[0024] Along the setting direction of the second bracket, a plurality of the oxygenation chambers are arranged from top to bottom, the water body flows through the plurality of oxygenation chambers in sequence, and the dissolved oxygen content is gradually increased in each of the oxygenation chambers.

[0025] As an improvement of the technical solution of the cascade reoxygenation dissolved oxygen control experimental device of the present invention, the oxygen stabilization system includes a constant pressure device and a conveying system;

[0026] The water flowing out of the oxygenation system is made to flow in the water pipe through a constant pressure device, and the flow rate is regulated by a valve.

[0027] A cascade reoxygenation dissolved oxygen control experimental method uses the cascade reoxygenation dissolved oxygen control device as described above; comprising the following steps: the water body becomes a low-saturation dissolved oxygen water body after passing through a deoxygenation module, the dissolved oxygen concentration of the water body is adjusted by the aeration system according to the dissolved oxygen concentration of the low-saturation dissolved oxygen water, and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system, and the experimental system obtains experimental data through the deoxygenation system, the aeration system and the oxygen stabilization system.

[0028] Beneficial effects of the present invention:

[0029] 1. The present invention adopts a compact deoxygenation reactor and a natural water flow continuous cascade oxygenation method, which can stably control and obtain experimental water bodies with multiple levels of dissolved oxygen concentration in a laboratory environment. The present invention significantly improves the deoxygenation efficiency in the process of mixing water and nitrogen, and can also meet the needs of flexibly adjusting the gradient dissolved oxygen level;

[0030] 2. The present invention is used in a laboratory environment, and has a simple structure, a convenient operation process, and a high oxygenation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the present invention;

[0032] Figure 2 It is a schematic diagram of the deoxygenation system in the present invention;

[0033] Figure 3 is a first experimental data diagram of an embodiment of the present invention;

[0034] Figure 4 is a second experimental data diagram of an embodiment of the present invention;

[0035] Figure 5 This is a third experimental data diagram of an embodiment of the present invention.

[0036] Explanation of the reference numerals: 1-nitrogen; 2-deoxygenation system; 3-oxygenation system; 4-experimental system; 5-water replenishment system; 6-reactor; 7-partition; 8-oxygenation chamber; 9-first bracket; 10-ejector; 11-second bracket; 12-diffusion tube; 13-oxygen stabilization system. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and beneficial effects of the present invention clearer, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0038] like Figures 1 to 4 As shown, the present invention provides a cascade re-oxygenation dissolved oxygen control experimental device, which adopts the principle of continuous cascade natural oxygenation to realize continuous control of dissolved oxygen in experimental water. The application scope of the device covers multiple disciplines such as aquatic biology, ecology, aquatic environmental toxicology, aquatic biological behavior and developmental ecology related to freshwater, seawater and sediment water bodies.

[0039] A cascade re-oxygenation dissolved oxygen control experimental device comprises: a deoxygenation system 2, an aeration system 3, an oxygen stabilization system 13 and an experimental system 4. The deoxygenation system 2 is used to generate a low saturation dissolved oxygen water body; the aeration system 3 is used to increase the dissolved oxygen content in the low saturation dissolved oxygen water body to obtain dissolved oxygen water bodies with different saturations; the oxygen stabilization system 13 is used to adjust the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body obtained by the aeration system 3; the experimental system 4 is used to simulate the aquatic ecosystem of the test environment, introduce the water body with a constant dissolved oxygen concentration into the experiment, and obtain experimental data;

[0040] Among them, the water body becomes a low-saturation dissolved oxygen water body after passing through the deoxygenation module. According to the dissolved oxygen concentration of the low-saturation dissolved oxygen water, the dissolved oxygen concentration of the water body is adjusted through the oxygenation system 3, and the pressure and dissolved oxygen concentration of the water body with a specific saturation dissolved oxygen are maintained through the oxygen stabilization system 13. The experimental system 4 obtains experimental data through the deoxygenation system 2, the oxygenation system 3 and the oxygen stabilization system 13.

[0041] The specific saturated dissolved oxygen water concentration refers to the saturated dissolved oxygen water that can be prepared in advance according to experiments.

[0042] In the present invention, dissolved oxygen control mainly includes two processes: oxygen separation and oxygenation. The oxygen separation effect is achieved through the deoxygenation system 2, and the oxygenation system 3 is used to achieve the oxygenation system, and the oxygen stabilization system 13, the water replenishment system 5 and the experimental system 4 are used to jointly achieve dissolved oxygen control.

[0043] In the experimental water, nitrogen 1 is injected to reduce the oxygen partial pressure in the water, thereby reducing the solubility of oxygen in the water and continuously escaping from the water until the oxygen partial pressure balance is reached again. After the oxygen separation treatment, the oxygen concentration of the water is gradually restored with the help of the cascade effect of natural water flow, so that experimental water with multiple dissolved oxygen concentration levels can be stably obtained.

[0044] The present invention includes a deoxygenation system 2, an oxygenation system 3 and an oxygen stabilization system 13, wherein the function of the deoxygenation system 2 is to rapidly generate a sufficient amount of low-saturation dissolved oxygen water; the oxygenation system 3 is responsible for achieving a continuous increase in dissolved oxygen in the low-oxygen water; and the oxygen stabilization system 13 is responsible for maintaining a stable pressure of the water entering the oxygenation system 3 and a constant flow state entering the experimental system 4.

[0045] Furthermore, the present invention also includes two parts: a water replenishment system 5 and an experimental system 4. The water replenishment system 5 uses the water replenishment system 5 to realize the automatic, continuous and stable input of raw water into the deoxygenation system 2. The experimental system 4 introduces water with a constant dissolved oxygen concentration into the aquatic ecosystem in the simulated test environment, and comprehensively reflects the effects of experimental water with different dissolved oxygen contents on the growth, reproduction and behavior of aquatic organisms (the types, quantity, growth stage and other factors of aquatic organisms need to be considered) at different exposure times, so as to ensure the accuracy and reliability of the experimental results.

[0046] In some embodiments of the present invention, the deoxygenation system 2 includes a gas supply system for supplying nitrogen 1, a reactor 6 and an ejector 10; the nitrogen 1 and the reaction water are sucked in through the ejector 10, and the reaction water is circulated and deoxygenated through a circulating water pump.

[0047] Further, the ejector 10 includes a convergent pipe, an air inlet, a diffuser 12, a check valve and a frequency converter;

[0048] The convergence pipe is arranged at the nozzle connection of the ejector 10 to guide the direction of the water flow. The air inlet of the ejector 10 is a vacuum suction roller structure. The ejector 10 sucks in the nitrogen 1 and mixes the reaction water.

[0049] In detail, the deoxygenation system 2 in the present invention is used in conjunction with the water replenishment system 5, and the water replenishment system 5 is responsible for automatically supplying water to the system. Inside the reactor 6, the water body and the nitrogen 1 are fully mixed through the action of the water circulation pump, thereby achieving a deoxygenation partial pressure balance and ultimately achieving deoxygenation. Preferably, the diffusion tube 12 is a circular pipe, with one end of the nozzle being wider as an inlet and the other end being narrow and flat as an outlet. The design of the diffusion section and the nozzle takes into account the injection angle and the uniformity of the injection, and is used to convert the high-speed jet into a circulating rising fluid, thereby further improving the efficiency of oxygen separation.

[0050] Among them, the water replenishment system 5 includes an external raw water pump, a solenoid valve switch, a liquid level sensor and a water pipeline. During the experiment, the reactor 6 obtains the actual liquid level of the cavity through the liquid level sensor, thereby controlling the solenoid valve to achieve automatic water replenishment. Among them, the solenoid valve and the liquid level sensor are connected by a circuit, and the start and stop of the reactor 6 water replenishment are controlled by pre-setting the high and low water level positions of the liquid level sensor. When the water level of the reactor 6 is reduced to the lowest water level, the solenoid valve is opened, and the water in the water storage tank is input through the raw water pump; when the water level of the deoxygenation reactor 6 reaches the highest water level, the solenoid valve is closed, and the raw water pump stops until the water level of the reactor 6 is reduced to the lowest water level and then opened again.

[0051] In the deoxygenation system 2, nitrogen 1 and reaction water are sucked in through the ejector 10, and the reaction water is further circulated and deoxygenated through the circulating water pump.

[0052] As a specific example of the present embodiment, the process of cyclic deoxygenation is that the circulating water pump takes water from the lower part of the reactor 6, and then transports it to a high place through a pipeline and divides it into two ways, and then it is processed by the ejector 10, and then enters from the bottom of the reactor 6 again. Since the convergence pipe is arranged at the nozzle connection of the ejector 10 to guide the direction of the water flow, the air inlet of the ejector 10 is a vacuum suction roller structure, and the ejector 10 sucks in the nitrogen 1 and mixes the reaction water. The ejector 10 forms a negative pressure through the vacuum suction roller structure, which can suck in the nitrogen 1 and make it fully mixed with the water body, thereby significantly improving the rate and efficiency of deoxygenation. Moreover, the injection angle of the diffusion pipe 12 entering the reactor 6 is designed to be inclined upward, which can make the flowing water body mediate and rise, thereby improving the mixing efficiency of the reaction water body before and after treatment.

[0053] In addition, the deoxygenation system 2 is arranged before the oxygenation system 3 and is installed on a first bracket 9. The height of the first bracket 9 is higher than that of the oxygenation system 3 to facilitate the flow of water.

[0054] As a specific example of this embodiment, the reactor 6 is a transparent organic glass container with a thickness of 6 mm, which can be conveniently observed inside the reactor 6. The main body of the reactor 6 is a cylindrical structure of 30 cm (diameter) × 60 cm (height), and its upper part is designed as a truncated cone of 30 cm (lower diameter) × 20 cm (upper diameter) × 10 cm (height). The opening is equipped with a sealing cover, which is tightly matched with the bolts and the sealing strip to ensure the sealing of the container. When necessary, the sealing cover can be opened to enter the inner cavity for cleaning.

[0055] Furthermore, two holes are opened in the center of the sealing cover, one of which is used to install a water level sensor and the other is used to install a one-way exhaust valve. The one-way exhaust valve can effectively exhaust the excess gas in the container through the exhaust pipeline, while preventing external air from entering the container. In addition, a manual ball valve is installed at the outlet of the reactor 6 to control the flow rate.

[0056] The gas supply system includes a pressure reducing valve, a gas cylinder and a gas supply pipeline. The gas supply pipeline is made of PVDF. The nitrogen 1 is high-pressure pure nitrogen stored in a steel cylinder. The flow rate of the nitrogen 1 entering the deoxidation reactor 6 is precisely adjusted by a gas pressure reducing valve. The nitrogen 1 bottle is connected to the pressure reducing valve through a thread, and the pressure reducing valve and the ejector 10 are connected in a plug-in manner through a three-way valve.

[0057] In some embodiments of the present invention, the oxygenation system 3 includes an aerator, which is divided into a plurality of oxygenation chambers 8 by a movable baffle, and each oxygenation chamber 8 is provided with a water outlet;

[0058] The aerator is arranged on a stand with adjustable height and / or angle;

[0059] Along the setting direction of the support, a plurality of oxygenation chambers 8 are arranged from top to bottom, and the water body flows through the plurality of oxygenation chambers 8 in sequence, and the dissolved oxygen content is gradually increased in each oxygenation chamber 8 .

[0060] As a specific example of the present embodiment, the aerator is made of high-strength glass with a thickness of millimeters, and its size is 1350 mm × 80 mm × 80 mm. The aerator is divided into a maximum of 9 oxygenation chambers 8 of equal size by 8 movable glass baffles, and a water outlet is installed on the side of each oxygenation chamber 8. The aerator is installed on a second bracket 11 with adjustable height and angle. After the installation is completed, the uppermost deoxygenation chamber is located just below the outlet of the reactor 6. In addition, when the dissolved oxygen concentration is lower than or exceeds the preset threshold, the alarm sounds an alarm.

[0061] In some embodiments of the present invention, the oxygen stabilization system 13 includes a constant pressure device and a delivery system; the water flowing out of the oxygenation system 3 is made to flow in the water delivery pipe through the constant pressure device, and the flow rate is regulated by a valve.

[0062] In detail, the water entering the aerator is delivered by a constant pressure pump, and the flow rate is precisely controlled by a precision valve. The water coming out of the aeration chamber 8 is connected to the experimental container through a pipeline, and an independently controlled valve is installed in the middle of the water delivery pipe to adjust the flow rate of the water entering each experimental container. In particular, a flow-through experimental system without an upper space is used as much as possible to isolate the air.

[0063] In some embodiments of the present invention, the experimental system 4 includes an experimental container and an overflow device.

[0064] As a specific example of this embodiment, the experimental container is a plurality of containers of the same size, which can be a glass beaker or a specific experimental container, and a suitable sealing cover is configured according to the shape of the container opening. In addition, in order to prevent the oxygen in the air from re-dissolving in the water during the experiment, no upper space is left between the overflow port and the sealing cover, and the sealing cover is installed with an overflow pipe entering the experimental container, and a hose is used to guide the experimental water into the circulation system. The experimental conditions should be as close as possible to the requirements of the standard, including water temperature, water quality, light, etc. For example, a temperature-controlled water bath can be selected to control the temperature of the experiment.

[0065] The present invention also provides a cascade reoxygenation dissolved oxygen control experimental method, using the cascade reoxygenation dissolved oxygen control device as described above, including the following steps: the water body becomes a low-saturation dissolved oxygen water body after passing through the deoxygenation module, and the dissolved oxygen concentration of the water body is adjusted by the oxygenation system 3 according to the dissolved oxygen concentration of the low-saturation dissolved oxygen water, and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system 13. The experimental system 4 obtains experimental data through the deoxygenation system 2, the oxygenation system 3 and the oxygen stabilization system 13.

[0066] In detail, first, the power of the deoxygenation system 2 and the water replenishment system 5 is turned on, and the deoxygenation reactor 6 in the deoxygenation system 2 is replenished with raw water for the experiment from the water storage tank. When the water level in the deoxygenation reactor 6 reaches the highest point, the water replenishment is stopped.

[0067] In the initial debugging stage, the nitrogen 1 pressure reducing valve and the frequency converter of the deoxygenation system 2 are opened, and the airflow entering the deoxygenation system 2 is initially adjusted to start pre-deoxygenation, so that the deoxygenation reactor 6 can reach a stable state. During the debugging process, the dissolved oxygen content of the deoxygenation reactor 6, the oxygenation chamber 8 and the experimental container is measured every 10 minutes using a handheld dissolved oxygen meter.

[0068] When the system runs stably, the flow rate of nitrogen 1 is adjusted through the oxygen separator and the gas pressure reducing valve so that the dissolved oxygen in the outlet water of the reactor 6 reaches a preset value.

[0069] To control the dissolved oxygen of the test system, after initial setup and deoxygenation, each experimental exposure vessel is slowly filled and continuously refreshed in the absence of test organisms. Experimental vessels ranging from 2 to 10 L can be used.

[0070] When the expected low dissolved oxygen water is obtained from the deoxygenation reactor 6, the slope angle, compartment distance, and compartment water level of the oxygenation device are precisely adjusted according to the difference between the dissolved oxygen concentration of the water in the experimental container and the preset level, and the flow rate of water in and out of the compartment is controlled until the dissolved oxygen concentration in the experimental container is consistent with the preset level.

[0071] Before the experiment begins, the controller water flow rate and the flow rate of nitrogen 1 are calibrated in the test commissioning. The first compartment is designated as the lowest dissolved oxygen level, which can be set to 1 mg / L. The subsequent cascade-increasing dissolved oxygen levels can be set to 2, 3, 4 and 5 mg / L, etc.

[0072] Among them, in this embodiment, the first compartment can be used as the first gradient, and so on, along the setting direction of the oxygenation chamber 8, from top to bottom, there are the first compartment, the second compartment, etc. In the present invention, the dissolved oxygen content of the specific saturation dissolved oxygen water body is the lowest, and the dissolved oxygen content of the specific saturation dissolved oxygen water body of the second compartment increases successively.

[0073] As a specific embodiment of the present invention, starting from the first gradient with a minimum of 0.5 mg / L, the concentration gradually increases to saturated dissolved oxygen 6-7 mg / L, with an increase of 0.5 to 1 mg / L. The number of compartments is selected according to actual needs, or the first compartment can also be 1 mg / L or other values, which are prepared according to experimental needs.

[0074] Accordingly, baffles may be repositioned, removed, or added as the temperature of the experimental system 4 changes, or when the flow rate of the compartments is altered.

[0075] In addition, the lead-out point can be selected according to actual conditions.

[0076] The following are some specific examples of using the present invention.

[0077] Example 1

[0078] Deoxygenation Rate: During the performance verification of Deoxygenation Reactor 6, the target dissolved oxygen was achieved within the first 10 minutes of operation, and most (>85%) of the dissolved oxygen in the raw water had been removed. The dissolved oxygen concentration of the raw water with a concentration of 7.00 mg / L was reduced to 0.95 mg / L within 10 minutes, then to 0.62 mg / L in 20 minutes, and finally 0.55 mg / L in 30 minutes during the applied deoxygenation cycle. These results formed the basis for the initial adjustment of the degassing system equilibrium time.

[0079] Example 2

[0080] Accuracy adjustment: The experimental device was tested without the use of an exposure container. The average DO concentration recorded during the 48h period was compared, and the results showed that DO remained relatively constant on the oxygenation chamber 8 of each gradient and remained similar between the data sets collected at two different times. The changes caused by non-constant flow conditions are not considered to be a problem with the performance of the device. The highest DO group will be used as a positive control. At nominal concentrations of 1mg / L or higher, the accuracy of the system is approximately 0.1mg / L, and the corresponding standard error is no greater than ±0.3mg / L.

[0081] Example 3

[0082] Temperature control system: It consists of 1 water bath, which can control the temperature of containers in 5 to 6 exposure chambers. The water temperature control is equipped with a temperature sensor and a water temperature controller. The water bath measures 1550*700*350mm and is made of 5mm Gaopeng glass. It can accommodate 5 test units. An overflow pipe with a diameter of 5cm is installed in the middle of the water bath, which can keep the water depth adjustable at 20cm. There is a drain with a diameter of 1.3cm at the bottom of the water bath. The required equipment includes a circulation pump, a temperature sensor, a temperature regulator and a water level sensor.

[0083] Example 4

[0084] Test unit: A container with a volume of about 10L (35cm long, 23cm wide, 18cm high) is a test unit. Four test containers are placed in each test unit. The test container is a 600mL glass beaker and a plexiglass cover. There is a 0.9cm hole on the cover, and an overflow pipe can be installed to extend below the liquid level. The upper part is covered with a 60-mesh nylon screen, and the lower part can be stuck on the beaker. The water in each aeration chamber 8 of the aeration device enters the test container at a constant pressure and stable flow rate. About 600mL of upper water in each container (including 100mL of sediment) is exchanged with the upper water in the water tank. During the 1-hour operation time, the calibrated flow rate flows into each test beaker at a rate of 32mL / minute. About 93% of the volume of the 150mL test beaker is updated during the 1h volume exchange time. Therefore, when the device is continuously operated for 24h per day, the renewal rate of the overlying water is about 8 volumes per day.

[0085] Example 5

[0086] In a research project on biological effects of dissolved oxygen, a 15-day chronic test on dissolved oxygen tolerance of aquatic organisms was conducted, in which the aeration device provided by the present invention was used to conduct chronic toxicity tests on aquatic organisms with multiple dissolved oxygen gradients.

[0087] Equipment setup: Start the equipment, the water first passes through the deoxygenation system 2 to reach an expected low dissolved oxygen level, and then the water enters the aeration module. After passing through the multi-stage aeration unit, the dissolved oxygen is gradually increased through natural water flow. The aeration device is installed on one side of the test system, and the water is transported to the aeration module through a constant pressure pump.

[0088] Operation process: When the system runs stably, the operation mode of the oxygen separator is adjusted to control the flow rate of nitrogen 1 so that the dissolved oxygen in the outlet water of the oxygen separation reactor 6 reaches the preset value of 1 mg / L. The slope angle, compartment spacing and water level of the aeration device are adjusted, and the flow rate of the water body is controlled at the same time, so that the dissolved oxygen concentration of the water body in different test containers reaches 6 preset levels: 1.5, 2.5, 3.5, 4.5, 5.0 and 6.0 mg / L.

[0089] Effect evaluation: After debugging, the dissolved oxygen of the 6 test groups was able to stabilize within the range of ±20% of the average value, and was able to reach the preset dissolved oxygen level: T1=1.46±0.28mg / L; T2=2.44±0.31mg / L; T3=3.62±0.20mg / L; T4=4.39±0.33mg / L; T5=5.10±0.23mg / L; T6=6.01±0.21mg / L.

[0090] Example 6

[0091] like Figures 3 to 5 As shown, the stability is demonstrated: The data provided in this example demonstrates the stability of the system at multiple solubility levels. The system has been successfully tested in a variety of aquatic toxicity tests such as gobies, midges, and white shrimp to determine its stability for chronic toxicity testing. Since these tests, the system has been in operation for 9 months and has been in operation for a maximum of more than 6 weeks. The system is basically automatic and only requires daily maintenance to replenish water lost by evaporation and replace nitrogen 1, which takes no more than 30 minutes per day.

[0092] Among them, Figure 3 As shown, in the dissolved oxygen toxicity test of goby, the control group T0 = 5.52 ± 0.13 mg / L; T1 = 4.55 ± 0.14 mg / L; T2 = 3.55 ± 0.15 mg / L; T3 = 2.47 ± 0.09 mg / L; T4 = 1.48 ± 0.11 mg / L; T5 = 1.01 ± 0.10 mg / L.

[0093] like Figure 4 As shown, in the dissolved oxygen toxicity test on chironomids, the control group T0 = 3.36 ± 0.04 mg / L; T1 = 2.94 ± 0.11 mg / L; T2 = 2.10 ± 0.10 mg / L; T3 = 1.30 ± 0.15 mg / L; T4 = 0.91 ± 0.13 mg / L.

[0094] like Figure 5As shown, in the dissolved oxygen toxicity test of white shrimp, the control group T0 = 5.02 ± 0.09 mg / L; T1 = 4.03 ± 0.12 mg / L; T2 = 2.99 ± 0.12 mg / L; T3 = 2.03 ± 0.11 mg / L; T4 = 1.05 ± 0.09 mg / L.

[0095] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

Claims

1. A cascade reoxygenation dissolved oxygen control experimental device, characterized in that: include: A deoxygenation system, wherein the deoxygenation system is used to generate a low-saturation dissolved oxygen water body; An oxygenation system, wherein the oxygenation system is used to increase the amount of dissolved oxygen in the low-saturation dissolved oxygen water body to obtain low-saturation dissolved oxygen water bodies with different dissolved oxygen; An oxygen stabilization system, the oxygen stabilization system is used to adjust the pressure and dissolved oxygen concentration of the water body with a specific saturation dissolved oxygen obtained by the oxygenation system; A test system, wherein the test system is used to simulate an aquatic ecosystem of a test environment, introduce a water body with a constant dissolved oxygen concentration into the experiment, and obtain experimental data; Among them, the water body becomes a low-saturation dissolved oxygen water body after passing through the deoxygenation module. According to the dissolved oxygen concentration of the low-saturation dissolved oxygen water, the dissolved oxygen concentration of the water body is adjusted by the oxygenation system, and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system. The test system obtains experimental data through the deoxygenation system, the oxygenation system and the oxygen stabilization system.

2. The cascade reoxygenation dissolved oxygen control experimental device according to claim 1, characterized in that: The cascade reoxygenation dissolved oxygen control experimental device also includes a water replenishment system; the water replenishment system is used to provide raw water for the deoxygenation system.

3. The cascade reoxygenation dissolved oxygen control experimental device according to claim 1 or 2, characterized in that: The deoxygenation system comprises a gas supply system, a reactor and an ejector for supplying nitrogen; Nitrogen and reaction water are sucked in through the ejector, and the reaction water is circulated and deoxygenated through the circulating water pump.

4. The cascade reoxygenation dissolved oxygen control experimental device according to claim 3, characterized in that: The ejector comprises a convergent pipe, an air inlet, a diffuser, a check valve and a frequency converter; The convergence pipe is arranged at the connection of the ejector nozzle to guide the direction of water flow. The air inlet of the ejector is a vacuum suction roller structure. The ejector sucks the nitrogen into the mixed reaction water.

5. The cascade reoxygenation dissolved oxygen control experimental device according to claim 3, characterized in that: The reactor is provided with a microporous structure unit for air and water intake, and the microporous structure unit is used to generate nitrogen and water into bubbles and water molecules, thereby prolonging the residence time of the bubbles and water molecules in water.

6. The cascade reoxygenation dissolved oxygen control experimental device according to claim 1 or 2, characterized in that: The oxygenation system comprises an aerator, which is divided into a plurality of aeration chambers by a movable baffle, and each of the aeration chambers is provided with a water outlet; The oxygenator is arranged on a second bracket with adjustable height and / or angle; Along the setting direction of the second bracket, a plurality of the oxygenation chambers are arranged from top to bottom, the water body flows through the plurality of oxygenation chambers in sequence, and the dissolved oxygen content is gradually increased in each of the oxygenation chambers.

7. The cascade reoxygenation dissolved oxygen control experimental device according to claim 1 or 2, characterized in that: The oxygen stabilization system includes a constant pressure device and a delivery system; The water flowing out of the oxygenation system is made to flow in the water pipe through a constant pressure device, and the flow rate is regulated by a valve.

8. A cascade reoxygenation dissolved oxygen control experimental method, characterized in that: Use the cascade reoxygenation dissolved oxygen control device as described in any one of claims 1 to 7; The following steps are included: The water body becomes a low-saturation dissolved oxygen water body after passing through the deoxygenation module. The dissolved oxygen concentration of the water body is adjusted by the oxygenation system according to the dissolved oxygen concentration of the low-saturation dissolved oxygen water, and the pressure and dissolved oxygen concentration of the specific saturation dissolved oxygen water body are maintained by the oxygen stabilization system. The test system obtains experimental data through the deoxygenation system, the oxygenation system and the oxygen stabilization system.

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